1. Field of the Invention
The present invention relates to a super absorbent polymer and a method of preparing the same.
2. Description of the Related Art
A super absorbent polymer is a functional resin having an ability of absorbing water of several tens to thousands of times the weight of the polymer and keeping the same therein, and thus, is broadly used in various products including—hygienic products such as sanitary goods, medical patches, agricultural absorbents, absorptive pads for foodstuffs, cable protective films, or the like.
The super absorbent polymer is generally used in a powder form, and when it is applied to a product, it is usually used in combination with a fibrous substrate made of natural fiber or synthetic fiber.
Such a super absorbent polymer is prepared and used as a type of hydrogel phase polymer with excellent physical properties. In general, the hydrogel phase polymer is obtained by a polymerization reaction of a raw material, followed by drying, grinding and classification processes to prepare a resin. In order to increase effects such as absorption properties, water retention ability, flow conductivity (i.e., permeability), etc., a variety of studies such as the provision of additional surface treatment processes, the alteration of different process conditions, etc. have been conducted.
Among such a process of preparing the super absorbent polymer, during a polymerization process, a number of oligomers having insufficiently increased molecular weight (waster-soluble fraction, ‘extractables’) may be generated in the resin. If the extractables exist in large quantity, these may be dissolved in water or the like, when the polymer is actually applied to products, hence causing a problem of being easily dissolved in water and eluted out of the products. In particular, when the polymer is applied to the hygienic product such as a paper (disposable) diaper, sanitary napkin, etc., or medical patches, it entails a problem of drastically deteriorating the performance of the product such as the induction of skin problems.
U.S. Patent Publication No. 2012-0035294 discloses a super absorbent polymer, however, did not solve some problems of a deterioration in physical properties such as water absorption and water retention abilities, and flow conductivity, and an induction of skin problems.